Firefighters called for the evacuation to higher ground of the Brazilian town hit by deadly mud flow from an earlier mining dam rupture, forcing 24,000 people to leave, as a second dam threatened to collapse.

Sirens began before dawn on Sunday, triggered by dangerous water levels at a tailings dam still standing in the Vale SA facility near Brumadinho in Minas Gerais state.

The evacuation efforts diverted attention from a search for hundreds of people missing after Friday’s dam burst unleashed a torrent of mud, burying the miner’s facilities and nearby homes, according to the fire department.

The search for survivors and bodies was suspended early Sunday amid fears a second dam owned by Brazilian mining giant Vale could break apart.

“Our work is completely focused on the evacuation,” Pedro Aihara, a spokesperson for the state fire department said.

Company employees at the mining complex were eating lunch Friday afternoon when the first dam gave way.

The confirmed death toll following the collapse has risen to 40, with up to 300 people missing, the fire department reported Sunday. Another 23 people were taken to hospital with injuries.

The muddy tailings of an iron ore mine swept past this market after the facility’s dam ruptured in Brumadinho on Friday, Jan. 25. (Leo Correa/Associated Press)

That already makes the disaster more deadly than a 2015 tailings dam collapse at an iron ore mine less than 100 kilometres to the east, belonging to Samarco Mineracao SA, a Vale joint venture with BHP Group.

That dam break spilled five times the mining waste into a more remote region, burying a small village and contaminating a major river in Brazil’s worst environmental disaster on record.

Relatives await news

All day Saturday, helicopters flew low over areas affected by Friday’s disaster as firefighters dug frantically to get into buried structures encased by a river of mud and mining waste.

“I’m angry. There is no way I can stay calm,” said Sonia Fatima da Silva, as she tried to get information about her son, who had worked at Vale for 20 years. “My hope is that they be honest. I want news, even if it’s bad.”

Da Silva said she last spoke to her son before he went to work on Friday, when around midday a dam holding back mine waste collapsed, sending waves of mud for kilometres and burying much in its path.

Here, the flow of waste can be seen in the community of Vila Ferteco in southeastern Brazil. (Leo Drumond/Nitro via AP)

She was one of scores of relatives in Brumadinho who desperately awaited word on their loved ones. Romeu Zema, the governor of Minas Gerais state, said by now most recovery efforts will entail pulling out bodies.

The flow of waste reached the nearby community of Vila Ferteco and an occupied Vale administrative office. On Saturday, rooftops poked above an extensive field of the mud, which also cut off roads.

Some residents barely escaped with their lives.

“I saw all the mud coming down the hill, snapping the trees as it descended. It was a tremendous noise,” said a tearful Simone Pedrosa, from the neighbourhood of Parque Cachoeira, eight kilometres from where the dam collapsed.

Pedrosa, 45, and her parents dashed to their car and drove to the highest point in the neighbourhood.

“If we had gone down the other direction, we would have died,” Pedrosa said.

“I cannot get that noise out of my head,” she said. “It’s a trauma … I’ll never forget.”